For my son, who loves building, and keeps building all over the place, at anytime with whatever is available (legos, kaplas, paper and adhesive tape, snow, sand, sticks, stones etc.). For example, we once had a cable car all made with paper and adhesive tape dividing half of our living room in two parts, when he was six.  
Sometimes, he puts things together in a different way, you would say it’s not going to work, but in the end, it does work. This inspired me for the formation “modified crown triangles”.